Numerical investigations on the role of the μ(I) viscoplastic rheology and the 3D frictional effects on a granular column collapse on large slopes
Résumé
The present work focuses on the modeling of dry granular flows in the context of the granular column
collapse in an inclined channel and detailed comparison with experimental thickness profiles and front
velocities. A nonlinear Coulomb friction term, representing the friction on the lateral walls of the channelis
added in the model, providing the ability to accurately simulate this column collapse on large slopes (up to
22 ◦ ). We demonstrate that accouting for lateral friction effect in the simulations is crucial at large slopes
(higher or equal to 16 ◦ ).
In other respect, we show that a Drucker-Prager constant viscosity model with a well-chosen value for the
viscosity is able to predict the slow propagation phase at large slopes, experimentally observed, whereas the
viscosity provided by the μ(I) rheology, evaluated from physical quantities, does not behave as well.
Finally, we show that the present model predicts the appearance of shear bands in the bulk when refining
the mesh. This behaviour appears to be unstable (as it induces shear bands as narrow as 4 grain diameter,
to the best of our refining capacities) but is not affecting the simulations in terms of velocity range and
free-surface movements. We also show that this effect is triggered by the coupling of the plasticity criterion
with the pressure field.
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